Acne

Definition and Diagnostic Criteria

Acne vulgaris is a chronic inflammatory skin condition primarily affecting the pilosebaceous units (hair follicles and their accompanying sebaceous glands). Diagnostic criteria include the presence of comedones (open or closed), papules, pustules, nodules, and in some cases, cysts. These lesions predominantly occur on the face, back, and chest. The severity of acne can be classified as mild, moderate, or severe based on the number and type of lesions.

Epidemiology

Acne is highly prevalent, affecting approximately 80% of individuals between 11 and 30 years old at some point. It commonly begins in adolescence due to hormonal changes that increase sebum production. While it typically resolves by the third decade of life, acne can persist into adulthood or even begin in adulthood. Women are more likely to experience adult-onset acne.

Diagnosis

Clinical features: Acne presents with a combination of non-inflammatory lesions (comedones) and inflammatory lesions (papules, pustules, nodules, and cysts). Comedones appear as small, flesh-coloured bumps (closed comedones) or as blackheads (open comedones). Inflammatory lesions are red and swollen, sometimes containing pus. Scarring and post-inflammatory hyperpigmentation are common sequelae.

Investigations: Diagnosis is primarily clinical based on the appearance and distribution of lesions. Hormonal investigations (e.g., androgen levels) may be warranted in cases of suspected endocrine disorders, such as polycystic ovary syndrome (PCOS).

Treatment

Mild acne: Topical treatments are the first line for mild acne, including benzoyl peroxide, topical retinoids (e.g., adapalene, tretinoin), and topical antibiotics (e.g., clindamycin). Benzoyl peroxide is often used in combination with topical antibiotics to prevent antibiotic resistance. Azelaic acid can also be an effective alternative.

Moderate acne: Moderate acne often requires systemic treatment. Oral antibiotics (e.g., tetracycline, doxycycline, or lymecycline) are commonly prescribed, typically for a duration of three months. Combining oral antibiotics with topical retinoids or benzoyl peroxide enhances efficacy. For females, oral contraceptives containing both oestrogen and anti-androgenic progestins can be effective.

Severe acne: Severe acne, characterised by nodules and cysts, may necessitate oral isotretinoin, a potent retinoid. Isotretinoin is highly effective but requires careful monitoring due to its potential for serious side effects, including teratogenicity, psychiatric effects, and lipid abnormalities. Referral to a dermatologist is recommended for severe cases.

Adjunctive treatments: Chemical peels, light therapy, and laser treatments can be beneficial for refractory acne and for managing scarring. Intralesional corticosteroid injections are an option for large inflammatory lesions.

Prognosis

The prognosis for acne varies. While many individuals experience improvement with appropriate treatment, the condition can be chronic and recurrent. Early and effective treatment is essential to minimise scarring and psychological impact. Post-inflammatory hyperpigmentation and scarring are common long-term sequelae that may require further intervention.